Cryptolepas rhachianecti Dall, 1872

Bosselaers, Mark & Collareta, Alberto, 2016, The whale barnacle Cryptolepas rhachianecti (Cirripedia: Coronulidae), a phoront of the grey whale Eschrichtius robustus (Cetacea: Eschrichtiidae), from a sandy beach in The Netherlands, Zootaxa 4154 (3), pp. 331-338 : 333

Cryptolepas rhachianecti Dall, 1872

Fig. 2

Cryptolepas rhachianecti Dall, 1872: 300

Cryptolepas rhachianectis Gruvel, 1903: 153 , pl. 2, figs. 4–10; pl. 3, figs. 10-11

Material examined. NHG 27 0 0 1, left latus or carinolatus collected from beach deposits in Zoutelande (Walcheren, The Netherlands), at the mouth of the River Scheldt.

Description and remarks. The size and aspect of this isolated left lateral or carinolateral compartment matches well the descriptions of the hard parts of Cryptolepas rhachianecti given by Pilsbry (1916), Zullo (1961, 1969), Davis (1972), Ross & Frick (2011) and Hayashi (2012). In particular, NHG 27 0 0 1 strikingly recalls the illustration of a cylinder-shaped specimen of C. rhachanecti , with very short external ribs, provided by Pilsbry (1916, pl. 66, figs. 2, 2a). Pilsbry (1916) described C. rhachianecti as follows: "[ C. rhachianecti ] differs [from Cetopirus complanatus and Coronula spp.] by lacking terminal flanges uniting the radial lamellae [i.e., the external ribs, or buttresses] into a solid outer wall, though there is sometimes a suggestive approach to this structure. [...] four to six ribs are seen on each compartment above. These ribs are denticulate along both sides. [...] They are finely striated vertically and crenulated at the basal edges. [...] The radii are as thick as the compartments [...]. The sheath is transversely grooved, a little shorter than the body-chamber, and its lower margin is not overhanging or prominent". Most of these characters can be clearly observed in NHG 27 0 0 1 ( Fig. 2 ) and, on the whole, they allow us to unambiguously attribute NHG 27 0 0 1 to C. rhachianecti . Nevertheless, the specimen from Zoutelande appears slightly damaged, and the external ribs are moderately eroded and worn (likely as a consequence of mechanical degradation in the current beach environment). Whereas extant coronulid shells are typically whitecoloured and rather translucent, the specimen here studied is brownish and strongly opaque; as such, it was likely affected by some process of early fossilization (e.g. recrystalisation or permineralisation).

Figures

FIGURE 2. NHG 27 0 0 1, Cryptolepas rhachianecti Dall, 1872, single left compartment (latus or carinolatus) collected from Recent beach deposits in Zoutelande (Walcheren, The Netherlands): a, alar view; b, external view; c, internal view; d, radial view; e, apical view. Scale bar: 5 mm. Scanning electron microscope (SEM) images by Julien Cillis, Koninklijk Belgisch Instituut voor Natuurwetenschappen, Brussels.